Self-controllable airfoil



Sept. 5, 1939. M. MjMUNK SELF-CONTROLLABLE AIRFOIL Filed Oct. 20, 1937 INVENTOR.

% W W K? Patented Sept. '5, 1939 UNITED STATES PATENT OFFICE 6 Claims.

This invention relates to airplanes, preferably monoplanes, in which the longitudinal control means are lodged in the airfoil.

It is an object of the present invention to provide for a simple and improved lift compensated longitudinal control, lodged in the airfoil. The general principle of such controls broadly is described in my copending application Ser. No. 140,238.

It is another object to provide for such self controllable airfoil having a high-lift device.

This is obtained by using flap means in rear of the center portion of the airfoil, ailerons in rear of the tip portions of the airfoil, sweeping the airfoil back in a manner to be described, and by using the flap means and the ailerons together for longitudinal control.

This, and other desirable objects and advantages of the present invention will be illustrated in the accompanying drawing and described in the specification, a certain preferred embodiment being disclosed by way of illustration only; for, since the underlying principles may be incorporated in other specific devices, it is not intended to be limited to the one here shown, except as such limitations are clearly imposed by the appended claims.

In the drawing, like numerals refer to similar parts throughout the several views, of which Fig. 1 represents the top view of a flying wing type airplane,

Fig. 2 is a schematic diagram of the flap and aileron control of the same airplane.

In Fig. 1, i0 designates the airfoil broadly, II the fuselage containing a closed cockpit l2, an engine l3, and a pusher propeller l4; ailerons I 5 and I5 hinged to the rear of the tip portion of the airfoil and flaps l6 and I6 occupy the rear portion of the airfoil area. There are fins H at the wing tips. The landing gear is not shown.

The ailerons and the flaps are operated by means of a control wheel 2i mounted on a control frame 22. The wheel is coupled to drum 23, governing the motion of control cable 24. is fastened to points and25' of d 26. Control frame or column 22 is turnably mounted in the cockpit, and its bottom ends 21 and 21' are connected by pushrods 23, 23', 23, and 23' to the ends 30 and 30' 'of levers 2i and 23', and to points 3| and 3| of levers "and 32'. The ends 33 and 33" of levers 32 and 32' are connected by means of pushrod 34 to the free end 35 of the locked hand lever 33.

driven by a pusher propeller, and

Horns 31 and 31' of the flaps, and 33 and 33 of the ailerons are connected-by pushrods 33, 39, 40, and 40' to the levers 26, 26', 32 and 32'.

It follows that the hand lever 36 turns the flaps down and up, without affecting the ail- 5 erons. Wheel 2| turns one aileron up and the other one down, without effecting the flaps. 'C0lumn 22 turns both flapsdown and simultaneously both ailerons up, these motions being inpredetermined ratio. v

Control wheel 2| is used in the usual manner for lateral control, and column 22 for longitudinal control,fwherebythe lift created by the parallel motion of the ailerons is compensated by the opposite motion of theflaps, The longitudinal control moment of ailerons and flaps is not zero, because the airfoil is swept back. That is to say, the tip portion ll of the airfoil is in rear of the center portion 42.

43 represents the center of gravity of the air,- 20

is in front of the aerodynamic center of all lift producing members of the airplane, in this case of the airfoil. As well known, the aerodynamic center is practically at or near the center of gravity of the airfoil area the same being supposed'to be concentrated at the 25% station points of the chords. The cen ter of gravity of the airplane is about. 8%, some percent more or less in front of this aerodynamic center. 43, is furthermore near the center of action of the flaps, which is near the 50% station of the mean chord of the center section, and as with all airplanes is two to ten percent of the mean aerodynamic chord ahead of the aerodynamic center of the airplane. With tailless monoplanes, this latter is of course the aerodynamic center of the airfoil itself. Hence, the average 25% point of the entire airfoil is not far from the average 50% point of the center section. This relation is provided by sweeping the wings back, as shown in the drawing.

The flaps I 6 and I6 move always parallel, as if they were bodily united. These flap means plane. This center are subdivided into two separate flaps in order to leave space free for the engine. Were'it not for that, one single flap extending from the outer end of flap l6 to the outer end of flap I3 would perform the same function as the pair of flaps, i6 and I6'., and would be entirely equivalent to said pair in aerodynamic respect.

I claim:

1. A tailless flying wing type monoplane comprising a swept back airfoil, flaps behind the center portion of said airfoil, ailerons behind The center of gravity of the airplane, 30

' ailerons in the opposite direction. the ailerons the tip or said airioil. means for operatlng the ailerons in opposite direction, and means for operating the ilaps in one direction and both terportion thereof, pitch control flap means, separate ,trol meansior actuating said first and second flap means. the center of gravity of 4 airplane being approximately at the avera e 50% chord station or said cen ving swe t-back trailing edge, wherebytheeflectoiaaidfirstfiapwhendev mm or-simstantial p tch mome fiying w mononlane comprising an anion and first fiap means behind and symmetrical with the center portion thereof, pitch control fiap means forming a part oisaid airfoil, separate control means for actuating said nrst 'on oi said airfoil. ailerons behindportion and and second flap means, the center of gravity of said monoplane being approximately'at the average 50% chord station of said center portion and said airfoil having whereby the eilect oi said first flap when depressed is tree of substantial pitching moments on the monoplane.

5. A, fiying wing type monoplane comprising an airfoil consisting of a fixed unmovable front portion, first fiap means behind andsymmetrical with the center portion thereof, pitch' control flap means forming a part of said airfoil, separate control means for, actuating said first and second fiap means, the center of gravity of said 1 monoplane being approximately at the average 50% station of the center portion of the airfoil a swept-back trailing edge and said airfoil having a swept-hack trailing edge whereby the eilect of said first flap means -when depressed is free of substantial pitching moments on thevmonoplane.

6. An airplane a center portion metrical with said center portion, pitch control flap; means, separate control means for actuating said first and second flap means, the center portion and said airfoil having a swept-back trailing edge, whereby the eiiect. of said first,

comprising airioilhaving consisting oi a fixed leading edge 7 portion and first flap meansbehindand sym-.

of gravity 01'] said airplane being approximately] at e average 50% chord station of said center 

